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<title>lwres_gabn</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
<a name="id2476275"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>lwres_gabnrequest_render, lwres_gabnresponse_render, lwres_gabnrequest_parse, lwres_gabnresponse_parse, lwres_gabnresponse_free, lwres_gabnrequest_free &#8212; lightweight resolver getaddrbyname message handling</p>
</div>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="funcsynopsis">
<pre class="funcsynopsisinfo">#include &lt;lwres/lwres.h&gt;</pre>
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
<tr>
<td><code class="funcdef">
lwres_result_t
<b class="fsfunc">lwres_gabnrequest_render</b>(</code></td>
<td>lwres_context_t *�</td>
<td>
<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnrequest_t *�</td>
<td>
<var class="pdparam">req</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *�</td>
<td>
<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *�</td>
<td>
<var class="pdparam">b</var><code>)</code>;</td>
</tr>
</table>
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
<tr>
<td><code class="funcdef">
lwres_result_t
<b class="fsfunc">lwres_gabnresponse_render</b>(</code></td>
<td>lwres_context_t *�</td>
<td>
<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnresponse_t *�</td>
<td>
<var class="pdparam">req</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *�</td>
<td>
<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *�</td>
<td>
<var class="pdparam">b</var><code>)</code>;</td>
</tr>
</table>
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
<tr>
<td><code class="funcdef">
lwres_result_t
<b class="fsfunc">lwres_gabnrequest_parse</b>(</code></td>
<td>lwres_context_t *�</td>
<td>
<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *�</td>
<td>
<var class="pdparam">b</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *�</td>
<td>
<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnrequest_t **�</td>
<td>
<var class="pdparam">structp</var><code>)</code>;</td>
</tr>
</table>
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
<tr>
<td><code class="funcdef">
lwres_result_t
<b class="fsfunc">lwres_gabnresponse_parse</b>(</code></td>
<td>lwres_context_t *�</td>
<td>
<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *�</td>
<td>
<var class="pdparam">b</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *�</td>
<td>
<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnresponse_t **�</td>
<td>
<var class="pdparam">structp</var><code>)</code>;</td>
</tr>
</table>
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
<tr>
<td><code class="funcdef">
void
<b class="fsfunc">lwres_gabnresponse_free</b>(</code></td>
<td>lwres_context_t *�</td>
<td>
<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnresponse_t **�</td>
<td>
<var class="pdparam">structp</var><code>)</code>;</td>
</tr>
</table>
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
<tr>
<td><code class="funcdef">
void
<b class="fsfunc">lwres_gabnrequest_free</b>(</code></td>
<td>lwres_context_t *�</td>
<td>
<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnrequest_t **�</td>
<td>
<var class="pdparam">structp</var><code>)</code>;</td>
</tr>
</table>
</div>
</div>
<div class="refsect1" lang="en">
<a name="id2543522"></a><h2>DESCRIPTION</h2>
<p>
      These are low-level routines for creating and parsing
      lightweight resolver name-to-address lookup request and
      response messages.
    </p>
<p>
      There are four main functions for the getaddrbyname opcode.
      One render function converts a getaddrbyname request structure &#8212;
      <span class="type">lwres_gabnrequest_t</span> &#8212;
      to the lighweight resolver's canonical format.
      It is complemented by a parse function that converts a packet in this
      canonical format to a getaddrbyname request structure.
      Another render function converts the getaddrbyname response structure
      &#8212; <span class="type">lwres_gabnresponse_t</span> &#8212;
      to the canonical format.
      This is complemented by a parse function which converts a packet in
      canonical format to a getaddrbyname response structure.
    </p>
<p>
      These structures are defined in
      <code class="filename">&lt;lwres/lwres.h&gt;</code>.
      They are shown below.
    </p>
<pre class="programlisting">
#define LWRES_OPCODE_GETADDRSBYNAME     0x00010001U
</pre>
<p>
    </p>
<pre class="programlisting">
typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
</pre>
<p>
    </p>
<pre class="programlisting">
typedef struct {
        lwres_uint32_t  flags;
        lwres_uint32_t  addrtypes;
        lwres_uint16_t  namelen;
        char           *name;
} lwres_gabnrequest_t;
</pre>
<p>
    </p>
<pre class="programlisting">
typedef struct {
        lwres_uint32_t          flags;
        lwres_uint16_t          naliases;
        lwres_uint16_t          naddrs;
        char                   *realname;
        char                  **aliases;
        lwres_uint16_t          realnamelen;
        lwres_uint16_t         *aliaslen;
        lwres_addrlist_t        addrs;
        void                   *base;
        size_t                  baselen;
} lwres_gabnresponse_t;
</pre>
<p>
    </p>
<p><code class="function">lwres_gabnrequest_render()</code>
      uses resolver context <em class="parameter"><code>ctx</code></em> to convert
      getaddrbyname request structure <em class="parameter"><code>req</code></em> to
      canonical format.  The packet header structure
      <em class="parameter"><code>pkt</code></em> is initialised and transferred to
      buffer <em class="parameter"><code>b</code></em>.

      The contents of <em class="parameter"><code>*req</code></em> are then appended to
      the buffer in canonical format.
      <code class="function">lwres_gabnresponse_render()</code> performs the
      same task, except it converts a getaddrbyname response structure
      <span class="type">lwres_gabnresponse_t</span> to the lightweight resolver's
      canonical format.
    </p>
<p><code class="function">lwres_gabnrequest_parse()</code>
      uses context <em class="parameter"><code>ctx</code></em> to convert the contents
      of packet <em class="parameter"><code>pkt</code></em> to a
      <span class="type">lwres_gabnrequest_t</span> structure.  Buffer
      <em class="parameter"><code>b</code></em> provides space to be used for storing
      this structure.  When the function succeeds, the resulting
      <span class="type">lwres_gabnrequest_t</span> is made available through
      <em class="parameter"><code>*structp</code></em>.

      <code class="function">lwres_gabnresponse_parse()</code> offers the same
      semantics as <code class="function">lwres_gabnrequest_parse()</code>
      except it yields a <span class="type">lwres_gabnresponse_t</span> structure.
    </p>
<p><code class="function">lwres_gabnresponse_free()</code>
      and <code class="function">lwres_gabnrequest_free()</code> release the
      memory in resolver context <em class="parameter"><code>ctx</code></em> that was
      allocated to the <span class="type">lwres_gabnresponse_t</span> or
      <span class="type">lwres_gabnrequest_t</span> structures referenced via
      <em class="parameter"><code>structp</code></em>.

      Any memory associated with ancillary buffers and strings for
      those structures is also discarded.
    </p>
</div>
<div class="refsect1" lang="en">
<a name="id2543667"></a><h2>RETURN VALUES</h2>
<p>
      The getaddrbyname opcode functions
      <code class="function">lwres_gabnrequest_render()</code>,
      <code class="function">lwres_gabnresponse_render()</code>
      <code class="function">lwres_gabnrequest_parse()</code>
      and
      <code class="function">lwres_gabnresponse_parse()</code>
      all return
      <span class="errorcode">LWRES_R_SUCCESS</span>
      on success.
      They return
      <span class="errorcode">LWRES_R_NOMEMORY</span>
      if memory allocation fails.
      <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
      is returned if the available space in the buffer
      <em class="parameter"><code>b</code></em>
      is too small to accommodate the packet header or the
      <span class="type">lwres_gabnrequest_t</span>
      and
      <span class="type">lwres_gabnresponse_t</span>
      structures.
      <code class="function">lwres_gabnrequest_parse()</code>
      and
      <code class="function">lwres_gabnresponse_parse()</code>
      will return
      <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
      if the buffer is not empty after decoding the received packet.
      These functions will return
      <span class="errorcode">LWRES_R_FAILURE</span>
      if
      <em class="structfield"><code>pktflags</code></em>
      in the packet header structure
      <span class="type">lwres_lwpacket_t</span>
      indicate that the packet is not a response to an earlier query.
    </p>
</div>
<div class="refsect1" lang="en">
<a name="id2543733"></a><h2>SEE ALSO</h2>
<p><span class="citerefentry"><span class="refentrytitle">lwres_packet</span>(3)</span>
    </p>
</div>
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